It is known to control the steering of track laying vehicles by selectively applying the brakes to one track or the other. However, new developments in drive train technology for track laying vehicles have made it possible to steer such vehicles during normal operation without relying on selective brake application. For example it is possible to steer a track laying vehicle through the use of a pair of infinitely variable transmissions (IVT) by varying the output ratio of an IVT connected to a first drive wheel relative to the output ratio of an IVT connected to another drive wheel. Such a system is highly effective in normal operation, however, in the event of a transmission failure this steering system might not be available. Some current track laying vehicle designs have a system by which the vehicle is steered in a straight line in the event of steering failure. Other track laying vehicles that travel at low speeds make no special provision for back up steering. However, various transportation regulations in place in some countries require that vehicle manufacturers provide some type of emergency or back-up steering means so that a vehicle can be steered in the event of such a steering system failure, until such time that the vehicle can be brought to a halt.
Accordingly, there is a clear need in the art for a back-up or emergency steering system for such track laying vehicles.